In general, power converters typically fall into one of three categories buck converters; boost converters, and buck-boost converters.
A buck converter is a step-down DC to DC converter, i.e., it converts a higher DC input voltage to a lower DC output voltage, and in general it is a switching mode power supply. In general a buck converter may be highly efficient, but it operates over a narrow range of input voltage, when the input voltage received from a voltage source is greater than the output voltage to be supplied to a load.
A boost converter is a set-up DC to DC converter, i.e., it converts a lower DC input voltage to a higher DC output voltage, and in general it is also a switching mode power supply. In general a boost converter may have a simple circuit structure and may provide a small ripple current at its input. However, like the buck converter it operates over a narrow range of input voltage, when the input voltage received from a voltage source is greater than the output voltage to be supplied to a load.
A buck-boost converter is a type of DC to DC converter that has an output voltage magnitude that can be either greater than, or lees than, the input voltage magnitude. In other words, a buck-boost converter includes both buck converter functionality and boost converter functionality.
In a conventional buck-boost converter, the buck functionality and boost functionality are not separate or independent from each other, but they share some important components such as the switching devices (e.g., MOSFETs, diodes, etc.), and therefore cannot be separately controlled or optimized. The conventional buck-boost converter exhibits some limitations in terms of its efficiency, a limited range of input and output voltages, and the number of applications to which it can be applied.
Thus, it would be desirable to provide a power converter which is capable in operating in a buck conversion mode and a boost conversion mode. It would also be desirable to provide such a power converter which is capable of operating with greater efficiency over a wide range of input and output voltages in many different applications.